[PATCH v8 2/3] regulator: Add devres version of of_regulator_get_optional()

[Chen-Yu Tsai]

On Thu, Sep 26, 2024 at 8:26 PM Andy Shevchenko
<andriy.shevchenko at linux.intel.com> wrote:
>
> On Thu, Sep 26, 2024 at 04:43:52PM +0800, Chen-Yu Tsai wrote:
> > On Wed, Sep 25, 2024 at 6:56 PM Andy Shevchenko
> > <andriy.shevchenko at linux.intel.com> wrote:
> > > On Wed, Sep 25, 2024 at 05:38:05PM +0800, Chen-Yu Tsai wrote:
>
> ...
>
> > > > +#if IS_ENABLED(CONFIG_OF)
> > >
> > > Do we really need this?
> >
> > What's the point of going through devres_* stuff if we already know
> > _of_regulator_get() is going to fail anyway?
>
> With devm_add_action*() this will be other way around and there are plenty of
> APIs done this way. The ifdeffery is simply ugly in the code.

It's still extra code that doesn't get compiled out.

> > Also, _of_regulator_get() does not have a stub version for !CONFIG_OF.
>
> So, what prevents us from adding it?

Because there's no need if the only internal user isn't using it.

I could also move them over to of_regulator.c.

_of_regulator_get() stays internal to that file, and devm_regulator_release()
gets exposed instead.

Does that sound better?

> > > > +static struct regulator *_devm_of_regulator_get(struct device *dev, struct device_node *node,
> > > > +                                             const char *id, int get_type)
> > > > +{
> > > > +     struct regulator **ptr, *regulator;
> > > > +
> > > > +     ptr = devres_alloc(devm_regulator_release, sizeof(*ptr), GFP_KERNEL);
> > > > +     if (!ptr)
> > > > +             return ERR_PTR(-ENOMEM);
> > > > +
> > > > +     regulator = _of_regulator_get(dev, node, id, get_type);
> > > > +     if (!IS_ERR(regulator)) {
> > > > +             *ptr = regulator;
> > > > +             devres_add(dev, ptr);
> > > > +     } else {
> > > > +             devres_free(ptr);
> > > > +     }
> > > > +
> > > > +     return regulator;
> > >
> > > Why not using devm_add_action() / devm_add_action_or_reset()
> > > (whichever suits better here)?
> >
> > Cargo cult from _devm_regulator_get() in this file. However since this is
> > meant to share the same release function, both functions need to use the
> > same mechanism.
> >
> > I could also argue that this is not an action, but an allocation, and so
> > devres_alloc() seems to make more sense.
>
> It's rather matter of the naming of the devm_add_action*() APIs, but again,
> we have plenty of APIs using it when it's allocation and not strictly speaking
> an action.

OK. Still the mechanism used needs to match that of the existing API.
So devres_add() it is for now.

> > > > +}
> > >
> > > > +#endif
>
> ...
>
> > > > +static inline struct regulator *__must_check devm_of_regulator_get_optional(struct device *dev,
> > > > +                                                                         struct device_node *node,
> > > > +                                                                         const char *id)
> > >
> > > I don't know the conventions here, but I find better to have it as
> > >
> > > static inline __must_check struct regulator *
> > > devm_of_regulator_get_optional(struct device *dev, struct device_node *node, const char *id)
> > >
> > > Similar to other stubs and declarations.
> >
> > I don't think there are any conventions. This file already has three types:
> >
> > 1. Wrap the line with the function name on the second line
> > 2. Wrap the arguments; wrapped arguments aligned to the left parenthesis.
> > 3. Wrap the arguments; wrapped arguments aligned with aribtrary number of
> >    tabs.
> >
> > I prefer the way I have put them.
>
> The way you put it despite relaxed limit is slightly harder to read.
> I don't remember many headers that do so-o indented parameters. Besides
> your way defers the burden of resplit to the future in case one more parameter
> needs to be added which will excess the 100 limit.
>
> Also __must_check is somehow misplaced in my opinion (talking from my
> experience and this can be simply checked by grepping other headers).

Seems correct to me. It's between the return type and the function name.
>From the coding style doc:

 __init void * __must_check action(enum magic value, size_t size, u8 count,
                                   char *fmt, ...) __printf(4, 5) __malloc;

The preferred order of elements for a function prototype is:

- storage class (below, ``static __always_inline``, noting that
``__always_inline``
  is technically an attribute but is treated like ``inline``)
- storage class attributes (here, ``__init`` -- i.e. section
declarations, but also
  things like ``__cold``)
- return type (here, ``void *``)
- return type attributes (here, ``__must_check``)
- function name (here, ``action``)
- function parameters (here, ``(enum magic value, size_t size, u8
count, char *fmt, ...)``,
  noting that parameter names should always be included)
- function parameter attributes (here, ``__printf(4, 5)``)
- function behavior attributes (here, ``__malloc``)


> That said, I prefer the way I suggested or something alike.

Two people arguing over style that is not clearly specified in the coding
style doc is probably wasting time. I'll use what `clang-format` gave:

static inline struct regulator *__must_check of_regulator_get_optional(
       struct device *dev, struct device_node *node, const char *id)
static inline struct regulator *__must_check devm_of_regulator_get_optional(
       struct device *dev, struct device_node *node, const char *id)


ChenYu